Electric switch



May 10, 1960 R. E. LARKIN 2,936,347

ELECTRIC SWITCH Filed Oct. 24, 1958 2 Sheets-Sheet 1 /5ZC 53/2 1 c 5 m4 144 3?. ma :4 a Q 5a g sza azb May 10, 1960 R E. LARKIN 2,936,347

ELECTRIC SWITCH Filed Oct. 24, 1958 2 Sheets-Sheet 2 I03. I06 I03 3 3 28 I loc 03 2.63 104 ELECTRIC SWITCH Application October 24, 1958, Serial No. 769,376

6 Claims. (Cl. 200-6) This invention relates to electric switches and more particularly to switches of the toggle actuated type.

While not limited thereto, the switches of the present invention are particularly adapted for coordinately controlling projection lamps and ventilating fans in movie and slide projectors.

A primary object of the invention is to improve and simplify the details of construction and assembly of the parts and the operating characteristics of the aforementicned type of switches.

A more specific object is to provide a novel and simple form of switch arrangement having two movable switch members combined with a common actuating member operable to selectively close or open either one or the other of the two switches, or to close and open both switches simultaneously. I

The accompanying drawings illustrate preferred embodiments of the invention which will be hereinafter described in detail, it being understood that the embodi' ments illustrated are susceptible of various modifications without departing from the scope of the claims.

In the drawings:

Figure 1 is a top plan view of an electric switch constructed in accordance with my invention;

Fig. 2 is a side elevational view of the switch shown in Fig. l; 1

Fig. 3 is a vertical sectional view to larger scale taken along lines 3-3 of Fig. 1;

Fig. 4 is a fragmentary view, partly in vertical section and partly in side elevation illustrating the position of the respective components with the actuating lever in its extreme right-hand position;

Fig. 5 is a perspective view illustrating the details of a part of the switch shown in Fig. 3;

Fig. 6 is a fragmentary view partly in vertical section and partly in side elevation illustrating the position of the respective components with the actuating lever in its extreme left-hand position;

Fig. 7 is a top plan view taken on line 7-7 of Fig. 3 ishowing the position of a part of the switch by broken mes;

Fig. 8 is a top plan view taken on lines 88 of Fig. 6 showing the position of a part of the switch by broken lines; and

Fig. 9 is a perspective View of a part of the switch shown in Fig. 3.

Referring to the drawings, the electric switch shown in Fig. 1 includes a casing consisting of a box like insulated switch base 10 having an upwardly opening recess 10a which is substantially closed by an overlying rectangular cover plate 12. The cover plate 12 is provided with a centrally located elongated rectangular opening 12a and a pair of upwardly extending lugs 12b situated on opposite sides of the opening 12a and parallel to the longitudinal dimension of the cover plate 12. The end portion 12c of cover plate 12 is further provided with laterally extending ears 12d which when assembled on base 10 coincide with the top outer marginal surfaces of the end d States Patent ice walls 10b of base 10. The base 10 has shallow external recesses located in the outer mid portions of its side walls 10d to accommodate a switch frame 14. The switch frame 14 is punched and stamped from sheet metal and is substantially saddle-shaped. When assembled on the base 10 as shown in Fig. 2, the top portion 14a of the switch frame 14 substantially overlies the cover plate 12 and provides means of securing cover plate 12 to the base 10. The depending leg portions 14b of switch frame 14 interfit with the extending cars 12 4! of cover plate 12 and cooperate to prevent endwise displacement of the cover plate 12 relative to the switch frame 14. The depending leg portions 1412 are positioned in respective shallow recesses 100 of the side walls 100! of switch base 10 and thereby prevent endwise displacement of the switch frame 14 relative to switch base 10, Each of the leg portions 14b is provided with a pair of integral downwardly projecting lugs or tongues 14c, the ends of which are bent inwardly into engagement with the lower surface of switch base 10 to secure switch frame 14 and cover plate 12 in assembled relationship to switch base 18.

As best shown in Fig. 3 the top portion of switch frame 14 is provided with an upwardly bulged central portion 14d which in turn is provided with a circular opening 14a to accommodate the reduced lower end 16a of an exteriorly threaded metal bushing 16. The reduced end 16a is spun outwardly as shown to rigidly and permanently connect the bushing 16 to the switch frame. Bushing 16 is formed at its upper end with an inwardly projecting annular flange 16b which permits upward insertion of an actuating lever 32 and provides a bearing surface for the spherical portion 32b of lever 32.

The aforedescribed lugs 12b extend upwardly from cover plate 12 into the lower end of bushing 16 when the cover plate 12 and switch frame 14 are assembled on base 10 and provide means for guiding and limiting the oscillatory motion of actuating lever 32 to a single plane parallel to the side walls lilb of base 10.

The switch mechanism comprises a fixed common terminal assembly 20 secured midway of the longitudinal dimension of the bottom wall we of base 10, fixed terminal assemblies 22 and 24 on opposite sides of terminal 20, a tiltable bridging contactor 26, a flexible contactor finger 28, a spring biased contactor operating plunger 30, and a manually operated actuating lever 32. The common terminal assembly 20 includes a U-shaped pivot member Ztla and a lug Ztlb which are electrically interconnected and secured to the upper and lower surfaces, respectively, of the bottom wall 102 of the base it) by a rivet 260. The bridging contactor 26 is interposed between the upwardly extending laterally spaced arms 2%! of the U-shaped member Zita and the substantially rectangular upwardly opening slots 20:: in arms 20d accommodate the respective laterally extending wing pertions 26a of the bridging contactor 26 to provide a pivotal support for the latter and to prevent its endwise displacement upon rocking or tilting of the bridging contactor 26.

As shown in Fig. 3, the left-hand stationary contact assembly 22 includes a lug 22a which is riveted to the outside oi the bottom wall we of base iii by a rivet 22b having an upset head seated against the inner surface of the bottom wall 10c of base 19 to provide a stationary contact 220. The right-hand stationary contact assembly 24 includes a lug 24a which is secured to the exterior of the bottom wall lile of base 10 by a rivet 2412 having an upset head seated against the inner surface of the bottom wall like of base 19 to provide a stationary contact post 240.

As shown in Fig. 5, a tiltable bridging contactor 26 formed of punched and stamped sheet metal is provided with extended arms 26b and 26c. Ann 26!) is provided with a contact tip 26d adapted to engage stationary contact tip 220 upon tilting of bridging contactor 26. The end portion 25c of arm 26c is bent downwardly substantially perpendicularly to arm 260 to form a stop or abutment for engagement with the interior surface of the bottom wall lite of base it to limit the degree of opening of contact tips 22c and 26d, respectively.

As best shown in Fig. 9 finger contactor 28 consists of a thin sheet of stamped bronze, copper, or other material of good electrical conductivity. Contactor 23 is used to complete an electrical circuit between the common terminal assembly 29 and the fixed terminal assembly 24. Contactor 23 has a rigid body portion 28a, an integral flexible arm portion 2815, an integral downwardly depending contact tip 230 and an integral mounting tab 280. to secure the contactor 28 to the bottom wall like of base 10. As shown in Fig. 7, the body portion 28a of the finger contactor 28 is disposed between one upwardly extending spaced arm Etta of the U-shaped pivot member 2! and the adjacent side wall 16d of base 19 and is coplanar with said sidewall. The mounting tab 28d which is bent perpendicularly to the body portion 23:: projects inwardly into the recess lite and lies parallel to the bottom wall the of base As shown in Fig. 3, the rivet 20c passes through aligned openings in the bottom wall We of base lit, the mounting tab Edd, and the overlying U-shaped pivot member 22a thereby securing the mounting tab be tween the U-shaped pivot member and the bottom Wall ltle of base in and electrically interconnecting the finger contactor 2S and terminal assembly 20. As shown in Fig. 9, the flexible arm portion 28b of finger contactor 28 is bent at an angle to the body portion 28a; and, within the cavity Eda of base it extends inwardly and downwardly toward stationary contact post 24c. The flexible arm portion 23b is provided with a depending contact tip 230 at its free end and the iorrner is bent in the aforedescribed manner to such a degree that the resulting self-bias of the arm portion 23b normally carries the integral contact tip 280 into tangential engagement with stationary contact post 24c to complete an electrical circuit between terminal assembly 2% and terminal assembly 24. The flexible arm portion 23b is further provided with an embossed cam 28c projecting laterally toward the center of the base it and extending along the mid portion of the length of arm 23!) to strengthen the arm 23b and to accelerate the separation of contact tip 280 from stationary contact post 240 as the contactor operating plunger 3% slides over the cam 28a and forcibly bends the contactor finger 253 out of the path of oscillatory movement of plunger 30 toward the side wall 152d of base lid.

The contactor operating plunger 30 is molded from a suitable insulating material and is provided with a cylindrical shaft 3% and an integral bullet-shaped tip 30b having a diameter approximately twice that of the shaft 39a. The bullet-shaped tip is provided with a hollow cylindrical top portion 3&0 and a depending solid conical section 36a. The contactor operating plunger 30 is slidably disposed in a downwardly opening recess 32a in the actuating lever 32 and is continuously biased downwardly into engagement with bridging contactor 26 by a coiled compression spring 34. The latter is held under compression between the top of recess 32a and the end of shaft Siia. The spring 34 also biases the actuating lever 32 upwardly causing the spherical portion 32b of said lever to bear upon the hereinbefore mentioned projecting annular flange 16b of bushing 16.

The actuating lever 32 comprises an integral machined metal member having a bat-shaped handle 320, a spherical portion 32b and a reduced cylindrical shank portion 32:! which is adapted to slidably carry contactor operating plunger 39. In the assembled relation shown in Fig. 3, the handle 320 of actuating lever 32 is inserted upwardly through the bushing 16, the spherical portion 32b is disposed within the bushing 16, and the depending shank portion 32d extends downwardly through the opening 12a in cover plate '12 into the cavity 10a of base 10.

Assuming that the actuating lever 32 is in its center position as shown in Fig. 3, the conical tip 30d of contactor operating plunger 30 is biased downwardly into engagement with the center portion 26 of bridging contactor 26 by compression spring 34, causing the arm portions 26b and 26c of the bridging contactor 26 to assume a substantially parallel relationship to the bottom of base 10. Thus the contact tips 220 and Zd are separated and the circuit between the common terminal 29 and the lefthand fixed terminal 22 is open. However, the plunger 39, in its center position (as shown in Fig. 7) allows the self-biased contactor finger 28 to engage the contact post 240 and complete a circuit between common terminal 20 and the fixed right-hand terminal 24. As the actuating lever 32 is moved toward its clockwise extreme position as shown in Fig. 4, the contactor operating plunger 30 slides over the left-hand arm 26b of the bridging contactor 26 causing said contactor to tilt about a pivot point provided by the cooperation of the marginal surfaces of the rectangular slots Ziie in the upwardly extending arms 2dr! of the U-shaped pivot member 20a and the laterally extending wing portions 26a of the center portion of the bridging contactor 26. When actuating lever 32 reaches its clockwise extreme position the spring biased plunger 30 forces the movable contact tip 26d downwardly into engagement with fixed contact tip 1220 thereby completing a circuit between common terminal 20 and the left-hand terminal 22. However, the flexible contactor finger 28 is not aflected by the above described movement of the actuating lever and remains in engagement with the righthand fixed contact 24c, thus providing a completed circuit between common terminal 20 and the right-hand terminal 24.

Operation of the actuating lever from its clockwise extreme position back to its center position as shown in Fig. 2, causes the plunger 39 to slide over the center portion 26 of bridging contactor 26 which in turn causes the left-hand arm 26b of said contactor to pivot upwardly out of engagement with fixed contact 22c. As the actuating lever 32 is moved toward its counterclockwise extreme position (as shown in Figs. 6 and 8) the plunger 3t) slides over the right-hand arm 260 of bridging contactor 26 causing its depending end portion 26d to be tilted downwardly to abut the bottom wall 106 of base 10 and bridging contactor contact tip 26a to be moved upwardly thus increasing its separation from fixed contact tip 220. Simultaneously, the outer wall of the cylindrical portion 300 of the bullet-shaped plunger tip 3% tangentially engages and slides over the embossed cam 282 on the arm 28b of the finger contactor 23 deflecting the self-biased flexible arm portion 28b and its contact tip 230 toward the adjacent side wall 10d of base 10, thereby disengaging the finger contactor contact tip 280 from the left-hand stationary contact post 24c.

The operational characteristics of the described switch permit selective completion and interruption of electrical circuits whereby the actuating lever 32 may be operated to its clockwise extreme position as viewed in Fig. 4 to provide a completed circuit between the common terminal 20 and both the fixed terminals 22 and 24. With the actuating lever 32 in its center position as shown in Fig. 3, the circuit between the common terminal 20 and the left-hand fixed terminal 22 is interrupted while the circuit between the common terminal 29 and the right-hand fixed terminal 24 remains completed. Finally, both circuits are interrupted as the actuating lever is moved to its extreme counterclockwise position as shown in Fig. 6. Thus the switch provides three operating conditions: off, one circuit completed, and two circuits simultaneously completed. The described switching arrangement provides a protective interlock whereby the circuit betwen the left-hand fixed terminal and the common terminal cannot be completed unless the circuit between the right-hand fixed terminal and the common terminal is also completed. Such a switching arrangement could be advantageously applied to a moving picture or slide projector, wherein the switch for a high wattage projection lamp could not be operated to circuit completing condition without concurrent operation of a ventilating fan switch to circuit completing condition, thereby preventing deleterious overheating of the projector.

I claim: 4

1. In an electric switch, in combination, a hollow insulating base, three spaced apart contacts mounted in said base on the bottom wall thereof, a first contactor movable about an axis parallel with said bottom wall to complete a circuit between a first and a second of said contacts, a second contactor normally completing a circuit between said first contact and the third of said contacts and having a portion secured to said first contact and a portion movable about an axis perpendicular to said bottom wall of said base to interrupt the last mentioned circuit, and means including a member oscillatable about an axis parallel with the first mentioned axis operable to move said first and second contactors as aforementioned selectively.

2. In an electric switch, in combination, an insulating base having an upwardly opening recess therein, three spaced apart stationary contacts carried by said base, a tiltable contactor loosely mounted on one of said stationary contacts and pivotally operable about an axis parallel with the bottom surface of said base to engage a second of said stationary contacts, a second contactor comprising a spring metal member secured to said one contact and having a portion thereof normally biased into lateral engagement with the third of said stationary contacts and movable against its bias about an axis perpendicular to the bottom surface of said base to disenage from said third contact, and operating means including a member oscillatable about an axis parallel with the bottom surface of said base to selectively operate said first and second contactors as aforementioned.

3. The combination according to claim 2, wherein said means for operating said tiltable contactor and said spring metal member comprises a plunger member slidably carried within a downwardly opening axial recess in said oscillatable member and biased downwardly into engagement with said tiltable contactor by a spring disposed in the last mentioned recess.

4. The combination according to claim 2, wherein said spring metal member comprises an integral mounting tab electrically interconnected with said one of said station ary contacts, an integral body portion bent perpendicularly to said mounting tab and extending upwardly toward the top of said recess, and an elongated integral arm portion extending from said body portion bent inwardly toward the longitudinal axis of said base and engaging with said third of said contacts.

5. The combination according to claim 3, wherein said plunger member comprises an elongated member of suitable insulating material having a shank portion disposed within said recess in said actuating lever and a substantially bullet-shaped tip integrally formed on its lower extreme, comprising a cylindrical portion the circumferential walls of which tangentially engage said spring metal member upon movement of said oscillatable member to force said spring metal member to move away from said third contact and further comprising a depending conical portion for continuously engaging said tiltable member as said plunger is carried over said tiltable member by pivoting said oscillatable member.

6. In an electric switch, in combination, an insulating base having an upwardly opening recess therein, a first stationary contact secured to the inside bottom wall of said base midway of its longitudinal dimension, a second stationary contact secured to said wall of said base at one longitudinal extreme, a third stationary contact secured to said wall of said base at its opposite longitudinal extreme, tiltable contactor loosely and pivotally supported by said first stationary contact providing means for completing an electrical circuit between said first and said second stationary contacts whereby said contactor is pivoted about said first stationary contact into engagement with said second stationary contact about an axis parallel to said bottom wall of said base, an elastically deformable finger-type contactor composed of a metal of good electrical conductivity having an integral mounting tab, said tab being positioned between said first contact and said base and electrically interconnected to said first contact, and having an integral body portion bent perpendicularly to said mounting tab and extending upwardly toward the opening of the aforementioned recess, and further having an elongated integral arm portion bent inwardly toward the longitudinal axis of said base and being normally biased by its elastic restoring energy to a closed position in which the free end of said arm portion engages said third stationary contact, and being pivotable about an axis perpendicular to that of said tiltable contactor, a pivotally operable actuating lever extending downwardly into said base comprising an elongated metal member having a downwardly opening axial recess and providing means for positioning said finger contactor and said tiltable contactor in relation to their respective associated stationary contacts, a contactor actuating plunger slidably carried in said recess of said actuating lever and continuously biased downwardly into engagement with the aforementioned tiltable contactor by a compression spring mem ber carried in said recess of said actuating lever, and having a shank portion disposed in said recess to engage said spring member and a substantially bullet-shaped tip on the lower extreme comprising an integral conical portion for engaging said tiltable contactor and an integral cylindrical portion the circumferential walls of which tangentially engage the finger contactor upon operation of said actuating lever thereby forcing .said finger contactor to move away from said third stationary contact against the self-bias created by bending said arm portion of said finger contactor, and a switch frame mounted on said base for pivotally supporting said actuating lever.

References Cited in the file of this patent UNITED STATES PATENTS 2,073,529 Sambelson Mar. 9, 1937 2,190,342 Smith Feb. 13, 1940 2,352,936 Bryant July 4, 1944 2,416,897 'Brady Mar. 4, 1947 2,647,177 Huck July 28, 1953 FOREIGN PATENTS 399,369 Italy Oct. 24, 1942 

